Demyelination The progress destruction of the myelin sheath surrounding the axons of neurons in both the CNS and PNS. These leads to a loss of sensation and motor control of the neuron. Multiple Sclerosis An autoimmune disorder in which the body's own immune system attacks and destroys the protective myelin coating, or myelin sheath, in various places along the central nervous system (demyelination). Myelin An insulating sheath around an axon that significantly increases conduction rate of action potentials. Myelin (damaged) Damage to the myelin sheath of an axon can result in an inhibition of the conduction of action potentials.